Recovery of normal ruminal biohydrogenation and de novo fatty acid synthesis following induction of milk fat depression in dairy cows
Open Access
- Author:
- Rico Navarrete, Daniel Enrique
- Graduate Program:
- Animal Science
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 26, 2013
- Committee Members:
- Kevin John Harvatine, Dissertation Advisor/Co-Advisor
Alexander Nikolov Hristov, Committee Member
Arlyn Judson Heinrichs, Committee Member
Michael Thomas Green, Special Member - Keywords:
- Biohydrogenation
dairy cows
milk fat depression
recovery - Abstract:
- The opportunity exists to improve production efficiency on dairy farms by implementation of strategies conducive to maximal milk fat yield. Diet-induced milk fat depression (MFD) was first recognized over 150 years ago, and represents an important economic loss to dairy farms because it results in milk fat production bellow the genetic potential of animals. This condition is the result of altered ruminal fermentation that leads to the formation of specific intermediates of biohydrogenation (BH) of unsaturated fatty acids that reduce mammary lipid synthesis. The observation of time course of recovery of milk fat synthesis and the timing of associated changes following an episode of MFD provides insight into the mechanism. Furthermore this knowledge is of great importance to management of the condition, as field nutritionists would benefit from understanding the time required to observe recovery after a dietary correction. The set of studies in the present dissertation characterized the time course of induction and recovery from MFD to be between 7 to 13 days and between 11 to 15 days, respectively. In addition, we identified the reduction in dietary concentration of polyunsaturated FA as the most important factor to correct in order promote restoration of normal BH and recover milk fat synthesis. Ruminal adaptation was corroborated as the rate-limiting step in the rate of recovery from MFD and the potential for dietary probiotics use to accelerate recovery of milk de novo fatty synthesis was demonstrated. Together, these experiments provide a set of key observations in regards to dietary factors associated to the recovery of milk fat synthesis and the restoration of normal ruminal biohydrogenation pathways.